Effect of preparation conditions on the nutrient release properties of alginate–whey protein granular microspheres

The effect of preparation conditions on nutrient release from alginate (AL)–whey protein isolate (WPI) granular microspheres obtained by an emulsification/internal cold gelation method was studied by varying WPI/AL ratio, microsphere diameter, total polymer concentration and riboflavin loading. Microsphere size distribution and nutrient encapsulation efficiency (EE) were examined. Riboflavin release profiles were investigated in simulated gastric and intestinal fluids. Values for EE above 80% were obtained for most microspheres, with the notable exceptions of high AL or pure AL. Variations in WPI/AL ratio, granule size and nutrient loading have major impact on nutrient release. Microspheres prepared with a WPI/AL ratio of 8:2, a riboflavin concentration of 1% in the initial aqueous phase and diameters near 94 μm retained the vitamin in SGF and released it in SIF. By careful process design, granular microspheres with potential as oral delivery vehicles for bioactive compounds may be developed.